Vibrating reed selector having improved contact configuration

ABSTRACT

A vibrating reed selector is disclosed which includes a housing, a motor assembly and a contact assembly wherein the contact assembly includes two vibrating tines, two contact brackets and a ceramic circuit board. Each tine carries a hook contact, each contact bracket carries a finger contact and the bracket and tines are arranged so that one finger contact is located between one hook contact and its supporting tine, and the other hook contact is located between its supporting tine and the other finger contact.

United States Patent Wiese 51 May 9,1972

[54] VIBRATING REED SELECTOR HAVING IMPROVED CONTACT CONFIGURATION [72] Inventor: Larry Lee Wiese, Pickerington, Ohio [73] Assignee: Bell Telephone Laboratories, Incorporated,

Murray Hill, NJ.

[22] Filed: Dec. 23, 1970 [21] Appl. No.: 101,003

[52] US. Cl ..335/97 [51] Int. Cl. ..H0lh 51/34 [58] FieldofSearch ..335/87, 88,90,9l,92,93,

[56] References Cited UNITED STATES PATENTS 2,877,319 3/1959 Bostwick eta] ..335/92 r 3,344,374 9/1967 White ...335/92 2,763,740 9/1956 Vazquez ..335/90 Primary Examiner-Harold Broome AttorneyR. J. Guenther and Edwin B. Cave [5 7] ABSTRACT A vibrating reed selector is disclosed which includes a housing, a motor assembly and a contact assembly wherein the contact assembly includes two vibrating tines, two contact brackets and a ceramic circuit board. Each tine carries a hook contact, each contact bracket carries a finger contact and the bracket and tines are arranged so that one finger contact is located between one hook contact and its supporting tine, and the other hook contact is located between its supporting tine and the other finger contact.

5 Claims, 21 Drawing Figures pair of magnetically responsive tines.

BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to contact arrangements in electromagnetically actuated vibrating reed selectors and pertains, in particular, to those in which the contacts are activated by a 2. Description of the Prior Art Vibrating reed selectors are advantageously used in paging devices and ordinarily contain one or more magnetic tines which vibrate in response to the application of an appropriate magnetic flux. Typically, the selectordelivers an output when the tines are driven towards resonant vibration by a triggering signal.

Vibrating reed selectors which are used in paging devices such as BELLBOY, or'the like, ordinarilycontain two tines. One tine is partof a contact set comprising the tine, a fixed contact and a moving contact. The tine carries the moving contact and swings toward and away from the other tine during vibration. As vibration approaches resonance, the moving contact is carried into engagement with the fixed contact thereby closing the contact set. When the contact set closes, a tone generating circuit is enabled and a paging signal is emitted in the form of an audible tone.

, A specific frequency is assigned to each paging device and the tines are tunedso that the contact set will close over a frequency band centered approximately on the assigned or resonant frequency. Bandwidth is determined by the length of time the contact set must remainclosed at the end frequencies andthe length of time the contact set must remain closed is in turn determined by the amount of power which must be delivered to the tone generating circuit in order for an audible tone to be generated.

, While designers have heretofore had a measure of freedom to adjust parameters such as bandwidth, power delivery rate and duration of contact closure, the latitude of adjustment has been slightjConsequently, it has been difiicult to design suitable selectors.

Accordingly, one object of this invention is to simplify the design of vibrating reed selectors.

While vibrating reed selectors are particularly useful in paging devices, many other applications arise where repetitive output pulses are useful. I-Ieretofore, the typical vibratingreed selector has been capable of only a single form of output pulse.'Thus, when the intended application called for different outputs, several selector types have been required. Providing a different selector for each application, however, is inherently wasteful and inefficient. Thus, it is advantageous if more than one form of outputpulse can readily be attained from a single selector.

Accordingly, another object of this invention, is to achieve variety in the output pulse forms available from a single vibrating reed selector.

SUMMARY OF THE INVENTION In accordance with a preferred embodiment of this invention, two contact sets are combined in a vibrating reed selectorso that one contactset closes in response to swing of the selector design, or electrically in series to decrease the dura- 'tion of contacticlosure and thereby'increase the number of available outputs.

According to one feature. of this invention, a sustained period of contact set closure is achieved during each cycle of vibration by connecting the contact sets electrically in parallel and adjusting the contact sets to close sequentially.

According to another feature of, this invention, a limited period of contact set closure is achieved at least once during each cycle of vibration by connecting the contact sets in series and adjusting thecontact sets to close simultaneously at least once during each cycle of vibration.

According to another feature of this invention, the fixed contact in one contact set is located between the moving contact and tine, and the moving contact in the other contact set is located between the fixed contact and the tine whereby one contact set will close when the tines swing inwardly and the other contact set will close when the tines swing outwardly.

DESCRIPTION OF THE DRAWING FIG. 1 is an exploded view taken in perspective of a vibrating reed selector embodying this invention;

FIG. 2 is a side elevation view with portions broken away and taken in section to show interior details of the selector shown in FIG. 1;

FIG. 3 is a plan view of the selector shown in FIG. 2 with portions broken away to show interior details;

FIGS. 4 through 7 schematically illustrate the mechanical interaction and electrical equivalent of the contact sets in the parallel mode of operation of the selector;

FIG..8 illustrates the output from the sequence shown in FIGS. 4 through 7 as it wouldappear over a hypothetical load FIGS. 9 through 12 schematically illustrate the mechanical interaction and electrical equivalent of the contacts in the series mode of operation of the selector; and

FIG. 13 illustrates the output from the sequence shown in FIGS. 9 through 12 as it would appear. over a hypothetical load L.

DETAILED DESCRIPTION Referring to FIG. I, a vibrating reed selector 10 is disclosed which comprises a contact assembly 20, a motor assembly 50, a housing assembly 70 and a cover 80. These components are combined to form a paging device which emits a paging signal in response to a triggering pulse. j

The contact assembly 20, as can be seen from FIGS. 1, 2

and 3, comprises a fork assembly 21, two contact brackets 22 and a circuit board 23. The fork assembly 21 is rigidly attached to the circuit board 23'as by brazing or soldering to metallic circuit paths thereon. It includes two. tines 24 rigidly attached at one end to opposite sides of a spacer block 25. The tines 24 and the spacer block 25 are made of a magnetic material such as Vibraloy. The tines 24, moreover, are flexible, magnetically responsive and tuned to vibrate in the presence of a magnetic field pulsating at the tuned frequency. The free ends of the tines 24 each has a hook contact 28 attached thereto. As best seen in FIG. 1, each hook contact 28 is substantially U-shaped and is rigidly attached to the fiat side of its supporting tine .24, as by welding. Advantageously, it is 0.005 mils in diameter and is formed from a piece of contact material such as rhodium contact wire. The spacer 25 is made of a magnetic material such as Permaloy and includes a shoulder 26 located between the two tines 24.

Each contact bracket 22, as shown in FIG. 1, is bent up at both ends to form a finger base 30 and a finger stop 31, respectively. Each is advantageously made of a material such as brass, and each includes a finger 32. The two fingers 32 function as fixed contacts and are advantageously made of rhodium contact wire 0.002 mils in diameter. As best seen from FIGS. 1 and 3, the fingers 32'are paired with the two tines 24 and the two hook contacts 28 to form two individual shoulder 34.

If desired, the finger 32 can be attached to the finger base 30 so that at rest it tangentually touches one side of the V finger 32 may be attached to the finger base 30 so that it lies on a line passing through the center of the shoulder 34. In that case, positioning the finger 32 on one side or the other of the shoulder 34 will again cause the finger to be deflected and thus internally biased. As will be made clear later, the specific position of each finger 32 with respect to its shoulder 34 is determined by the particular mode of operation selected and the condition of the mating surfaces on the finger 32 and its associated hook contact 28.

The circuit board 23 is made from a ceramic material and supports the fork assembly 21 and the contact brackets 22 in operative relationship to each other. By using a ceramic material, thermal characteristics are improved. While many ceramic materials will be suitable, it has been discovered that one with a coefficient of thermal expansion of 7.7Xl, such as Alsigmag 771, is most advantageous.

As best seen in FIG. 3, the circuit board 23 includes circuit paths 35, 36, 37, 38 and 39 which are advantageously made from nickle which is plated on the surface thereof. When the fork assembly 21 is mounted on the circuit board 23, the circuit paths 35 and 36 will be electrically in contact with the tines 24. Similarly, the circuit path 37 will be electrically in contact with both contact brackets 22. Finally, the circuit paths 35, 38 and 39 are all electrically linked to connector pins in the housing assembly 60. Advantageously, each of the circuit paths 35, 38 and 39 encompasses a notch cut in the circuit board 23. Additional circuit paths (not shown) are associated with both circuit paths 39 and extend along the undersurface of the circuit board 23 to a position approximately beneath the contact brackets 22.

All of the circuit paths except 39 include strapping terminals; i.e., the circuit path 35 includes a strapping terminal 40, the circuit path 36 includes two strapping terminals 41 and 42, respectively, the circuit path 37 includes a strapping terminal 43 and the circuit path 38 includes a strapping terminal 44. By appropriately connecting the strapping terminals, the two contact sets in the contact assembly 20 can readily be connected in parallel or in series electrically.

The circuit board 23, is slotted at one end to facilitate assembly with the motor assembly 50. It serves as support for the contact brackets 22 which can be soldered in place or held by screws. Where screws are used, the circuit board 23 is drilled and tapped to accommodate four mounting screws 45. The mounting screws 45 fit in the slots 33 and hold the contact brackets 22 adjustably on the circuit board 23 and electrically in contact with the circuit paths 37. When the contact brackets 22 and the fork assembly 21 are attached to the circuit board 23, the contact assembly 20 becomes a single unit which is readily adapted for modular use if desired.

The motor assembly 50, as shown in FIG. 1, comprises a core 51 and a bobbin 52. The core 51 is associated with an end magnet 53 and includes a pole piece 54. Both are made of a magnetic material and the end magnet 53 advantageously has an H-configuration to accommodate at opposite ends the core 51 and the tines 24 and spacer block 25.

The core 51 is substantially L-shaped to form the pole piece 54. The pole piece 54, as best seen in FIGS. 1 and 3, is notched to accommodate the slot in the circuit board 23 so as to hold one end of the contact assembly 20 in place. The other end of the core 51, like the spacer block 25, has cross-sectional dimensions such that it will fit snuggly in one of the spaces between the legs of the I-I-shaped end magnet 53. The end magnet 53, therefore, serves to physically join the other end of the contact assembly 20 to the motor assembly 50,

while magnetically linking the core 51 and spacer block 25 and tines 24.

The bobbin 52 has a hollow center to accommodate a portion of the core 51 extending away from the end magnet 53 and includes two end flanges 55 and two terminal pins 56. One

of the end flanges 55 is notched to accommodate the terminal 'pins 56 as well as portions of thecore 51 in the vicinity of the pole piece 54. The terminal pins 56 are advantageously made of a flexible material such as phosphor bronze. As best seen in FIG. 1, one end serves as a terminus for a coil 57, while the other end is curved to engage one of the circuit paths previously described as being located on the underside of the circuit board 23 and which is associated with the circuit paths 39.

Advantageously, the curved ends of the terminal pins 56 are soldered to their respective circuit paths on the circuit board 23. Alternatively, however, the connection may be a pressure or friction contact, if desired. The coil 57 is wound over the bobbin 42 and is designed to supply a magnetic flux to the core 41 when current flows into one of the circuit paths 39 and out the other in response to an appropriate triggering signal.

The housing assembly 70 accommodates the motor assembly 50 and the contact assembly 20. As best seen in FIG. 1, it comprises a body shell 71 adapted to receive the cover 80. Both the body shell 71 and the cover are made of an insulating material and the body shell 71 includes a shoulder or lip which fits inside the cover 80 when the cover 80 is installed. As best seen in FIG. 1, the body shell 71 is equipped with four connector pins 73 which are linked electrically to the contact assembly 20 by four wire leads 74 and 75, respectively.

The wire leads 74 and 75 are all made of an electrically conducting material such as phosphor bronze. Moreover, they are curved at one end and have a hook at the other. The curved end is adapted to be fixedly attached to a connector pin 73 as by soldering and the hooked end is adapted to engage one of the notches on the circuit board 23. As shown in FIG. 3, the wire leads 74 are associated with the circuit paths 39 and the wire leads 75 are associated with the circuit paths 35 and 38, respectively. As described earlier, the circuit paths 39 are electrically linked to the coil 57 through the terminal pins 56.

If desired, as best seen in FIG. 2, the wire leads 74 and 75 can be made of a rigid yet flexible material so that thecurvature of each will exert a biasing force which draws the circuit board 23 into the body shell 71. In such an event, the contact assembly 20 and the motor assembly 50 will be simultaneously pulled together tightly and into the housing assembly 70. Thus, the wire leads 74 and 75 can be made to serve a dual function, i.e., to electrically link the connector pins 73 to the contact assembly 20 while simultaneously holding the components together. In such a case, the flexible nature of the wire leads 74 and 75 will exhibit a shock absorbing characteristic whereby stray forces can readily be absorbed which might otherwise tend to separate the contact assembly 20 and motor assembly 50 from each other or the housing assembly 70.

At least two modes of operation are possible with the embodiment described, i.e., with the two contact sets connected electrically in series or electrically in parallel. Selection of either configuration is readily made merely by appropriately strapping the circuit path terminals and adjusting the position of the contact brackets 22. Each configuration will produce a distinctive output.

In the configuration shown in FIG. 3,.. for example, the vibrating reed selector 10 is adapted for operation in the parallel mode. In parallel operation, straps have been added to electrically link the strapping terminals 40 and 41 and the strapping terminals 38 and 43, respectively. In addition, the contact brackets 22 are positioned on the circuit boards 23 so that the fingers 32 do not touch the hook contacts 28 and so that one finger is located between the contacting portion of one hook contact 28 and one tine 24, and the other hook'contact 28 is located between the other finger 32 and the other tine 24.

With the contact brackets 22 positioned and the strapping tenninals connected as described, the two contact sets will be electrically in parallel and current flowing into the circuit path 35 from one wire lead 74 will be divided between the two tines 24 by the strap linking the strapping terminals 40 and 41. Consequently, when the contact set containing either tine 24 is closed, the current will be returned to the other wire lead 74 by passing through the circuit paths 37 and 38 via the straps linking the strapping terminals 43 and 44.

The parallel'mode of operation is schematically illustrated in FIGS. 4 through 7. FIGS. 4A through 7A, for example, illustrate the structural interaction of the two contact sets through one cycle of vibration. Similarly, FIGS. 48 through 78 illustrate the electrical equivalent of the situation illustrated in FIGS. 4A through 7A. FIG. 8 illustrates the electrical output for each condition in the foregoing sequence.

Energizing the coil 57 with the appropriate triggering pulses will drive the tine 24 toward resonant vibration in a conventional manner. Inthe sequence illustrated in FIGS. 4 through 7, the tines 24 are vibrating at or close to their resonant frequency. At the beginning of the vibration cycle, the fingers 32 are unequally spaced from the tines 24 and, as illustrated in FIG. 4A, there is no initialcontact with the hook contacts 28 Thus, as can be seen from FIG. 43 both contact sets are open and, as shown in FIG. 8, no current will flow through a hypothetical load L (such as a tonegenerating circuit).

As the tines 24 begin to vibrate, they first swing toward one another. As illustrated in FIG. 5A,'the hook contact 28 which is located between its tine 24 and finger 32 will move in a direction away from engagement, while the other finger 32, which is located between its hook contact 28 and tine 24, will move into engagement with its hook contact 28 and thus close an electrically conducting path linking the wire leads 74.

At the completion of a half cycle, the tines 24 will return to their initial or normal position. As illustrated in FIGS. 6A and 68, both contact sets will open so, as shown in FIG. 8, no current can flow through the hypothetical load L.

To complete the cycle, the tines 24 leave the initial position and begin to swing apart. As illustrated in FIG. 7A, the other hook contact 28 will now engage its finger 32, while the first hook contact 28 will move further away from its associated finger 32. Nevertheless, because the two contact sets are connected electrically in parallel, a current will again flow between the wire leads 74 as illustrated in FIG. 8.

From the foregoing, it is apparent that the contact sets in the disclosed embodiment close during both half cycles of vibration. As a consequence, current will flow twice during each cycle thereby making availabletwice as much power as can be obtained from contact sets which close only once in each cycle. As an additional safety feature, moreover, if one contact set fails to close, the remaining one will still function. Thus, a substantial margin of safety is provided over conventional selectors which contain only a single contact set or contact sets which close simultaneously. s

As indicated earlier, the disclosed vibrating reed selector 10 can also operate in at least one other mode, i.'e., a series mode. The series mode of operation is schematically illustrated in FIGS. 9 through 12. FIGS. 9A through 12A, for example, illustrated the structural operation of the contact sets, while FIGS. 98 through 123 illustrate the electrical equivalence for each step in the sequence shown in FIGS. 9A through 12A. Finally, FIG. 13 displays the output over a hypothetical load L, such as a tone generating circuit, for each step in the illustrated sequence.

As in the parallel mode of operation, the two contact sets are depicted at various stages throughout one cycle of vibration at or close to the resonant frequency. As shown in FIG. 9A, the contact brackets 22 have initially been adjusted so that the hook contacts 28 and the fingers 32 in both contact sets are in engagement and so that the fingers 32 are equally spaced from the tines 24. The strapping between strapping terminals, moreover, has been rearranged so that only the strapping terminals 42 and 44 are electrically linked.

When the contact sets are'in the initial state, as described and illustrated in FIG. 9A, current from one wire lead 74 reaches the other by flowing in appropriate serial order through the circuit paths 35, 36, 37 and 38, the two fingers 32, the two tines 24 and the two hook contacts 28. When that occurs, current, as illustrated in FIG. 13, will flow from one lead wire 74 to the other.

During the inswing and outswing of the tines 24, as shown in FIGS. 10A and 12A, however, only one contact set at a time will be closed. Consequently, as shown in FIG. 13, no current will flow during either half of the vibration cycle.

At mid-cycle, however, the tines 24 will again return to their initial state and, as illustrated in FIG.. 11A, the two contact sets will simultaneously close for an instant. As a consequence, the series circuit illustrated'inFIG. 118 will be enabled and a short or spiked pulse will appear in a load L as shown in FIG. 13. I

Alternative arrangements of the fingers 32 are readily possible. As is apparent from FIG. 3, the fingers 32 are located on opposite sides of the shoulders 34. That relationship, as will be seen by comparing FIGS. 4A and 9A, will not change regardless of the mode selected for operation. Instead, the contact brackets 22 need only be adjusted and minor strapping changes efiected in order to change modes. Moreover, it will be recognized that so long as the relative positions of the fingers 32 are maintained, their respective positions can be reversed without any affect on operation. Consequently, surfaces which heretofore have not been involved in the contacting operation can be mated with corresponding new contacting surfaces on the respective hook contacts 28 merely by flipping the fingers 32 to the opposite sides of the shoulders 34 and readjusting the positions of the contact brackets 22. As a result, longer contact life can readily be achieved with the configurations illustrated.

In summary, operations of the vibrating reed selector 10 in the parallel mode will increase the duration of contact engagement in each cycle of vibration thereby increasing selector efficiency. Moreover, the selector can readily be adapted to function in at least one other operating mode from which an entirely different output is readily obtained, i.e., a spiked pulse when operated in the series mode. Accordingly, the disclosed invention not only relieves design restrictions by increasing the duration of contact closure, but has inherent capabilities for use in other heretofore unavailable applications. While only two embodiments of the invention have been disclosed, it will be readily understood that they merely illustrate preferred applications of the principles of the invention and that other arrangements falling within the scope of the invention will readily occur to'those'skilled in the art.

What is claimed:

l. A vibrating reed selector having two contact sets wherein each contact set includes a vibrating tine arranged toswing toward and away from a corresponding tine inthe other contact set when said tines are magnetically stimulated, a moving contact mounted on said tine so as to be cyclically reciprocated along a predetermined path, a fixed contact for closing said contact set when engaged by said moving contact and support means for positioning said fixed contact in the path traversed by said moving contact characterized in that said fixed contacts are disposed in predetermined positions with respect to said tines and one tine includes means for closing one contact set in response to swing of said tines toward one another and the other tine includes means for closing the other contact set in response to swing of said tines away from each other whereby the duration of contact set closure can be changed merely by changing the position of said fixed contacts andconnecting said contact sets in series or in parallel electrically."

2. A vibrating reed selector in accordance with claim 1 wherein the fixed contact in one contact set is located between its associated tine and moving contact and the moving contact in the other contact set is located between its associated tine and fixed contact whereby the moving contact in said one contact set will engage its associated fixed contact when said tines swing toward one another and the moving contact in said other contact set will engage its associated fixed contact when said tines swing away from each other.

3. A vibrating reed selector in accordance with claim 2 wherein said contact sets are connected electrically in series and said fixed contacts are squally spaced from said tines and said contact sets will simultaneously close during some portion of each cycle of tine vibration.

5. A vibrating reed selector in accordance with claim 1 wherein each of said means for closing comprises a U-shaped portion at the end of a moving contact.

t ts-we 

1. A vibrating reed selector having two contact sets wherein each contact set includes a vibrating tine arranged to swing toward and away from a corresponding tine in the other contact set when said tines are magnetically stimulated, a moving contact mounted on said tine so as to be cyclically reciprocated along a predetermined path, a fixed contact for closing said contact set when engaged by said moving contact and support means for positioning said fixed contact in the path traversed by said moving contact characterized in that said fixed contacts are disposed in predetermined positions with respect to said tines and one tine includes means for closing one contact set in response to swing of said tines toward one another and the other tine includes means for closing the other contact set in response to swing of said tines away from each other whereby the duration of contact set closure can be changed merely by changing the position of said fixed contacts and connecting said contact sets in series or in parallel electrically.
 2. A vibrating reed selector in accordance with claim 1 wherein the fixed contact in one contact set is located between its associated tine and moving contact and the moving contact in the other contact set is located between its associated tine and fixed contact whereby the moving contact in said one contact set will engage its associated fixed contact when said tines swing toward one another and the moving contact in said other contact set will engage its associated fixed contact when said tines swing away from each other.
 3. A vibrating reed selector in accordance with claim 2 wherein said contact sets are connected electrically in series and said fixed contacts are squally spaced from said tines and in initial contact with said moving contacts whereby said contact sets will simultaneously close during some portion of each cycle of tine vibration.
 4. A vibrating reed selector in accordance with claim 2 wherein said contact sets are connected electrically in parallel and said fixed contacts are unequally spaced from said tines and initially separated from said moving contacts whereby said contact sets will simultaneously close during some portion of each cycle of tine vibration.
 5. A vibrating reed selector in accordance with claim 1 wherein each of said means for closing comprises a U-shaped portion at the end of a moving contact. 